Pulp article and method of manufacture



March 21, 1939. M. P cHAPLlN PULP ARTICLE AND METHOD OF MANUFACTUREFiled April 9, 1957 INVENTOR ATTORNEYS.

Zlgff' Patented Mar. 21, 1939 UNITED STATES PATENT ol-i-"ici-V MAN'UFAMerle r. Chaplin, smith romana mim, suunor, by mesne toTheCanalNa-'assignments, tional Bank of Portland, Portland, Maine, a

national banking association Applicaties April s, 1931, sensi N. 135.906

s claim.` (ci. sz-ss) This invention relates to a new article ofmanufacture, moulded from cellulose materials having specialcharacteristics, produced'by a method which is simple and inexpensive,resulting in an article having useful and unique characteristics.

The article produced by the method hereinafter disclosed may be in theform of a plate, dish, or like container and is particularly adapted foruse in the cooking, serving or storing of l0 -foods and food productsand more particularly those which contain oils. fats and greases.

A further useful and valuable purpose served by the article of thisinvention, is that'itslow cost permits it to be discarded after singleuse avoiding the necessity of cleaning or washing a container, the costof which necessitates its being used over and over again. 'Ihis isparticularly desirable where the container is used for the cooking ofcertain foods which become gummy or sticky during the cooking processand which adhere to the utensil in which they are prepared.

Various solutions to the problems of producing an inexpensive containerfor the above purposes have been suggested but all fall'short of thedesired result.

Some of the expedients suggested include the use of expensive chemicalsfor treating or impregnating the material of the container eitherbefore, during or after manufacture. Other expedients include theintroduction of non-cellulosic materials such as glue, infusorlalearths, alkaline or other fillers, either mixed with the cellulosematerials or used as a film or layer.

Other materials include aluminum and titanium silicate as well as thesulphates of aluminum, iron, sodium and other materials. Most of thesematerials require that the article be impregnated therewith for a periodof time and subsequently 40 dried, some materials requiring two or morekimpregnations with subsequent drying.

Some other suggested expedients include the cutting out-of paper blanksand the coating of these blanks with pigments, paints, casein, rosin,

silicates and other materials, and the assembly of these blanks underpressure to form the desired article. This method is not only wastefulof ma-y i terial but involves costly manufacturing operations.

Another expedient is to coat the surface -of a previously formed anddried'plate or dish. with an enamel or other coating attempting by thismeans to protect the article from attack and disintegration by the foodproducts which it must be 5'5 adapted to resist. Various other processesand materials and substances have beenuested, these being too numerousto mention.

Peculiarly enough, one of the most useful and efilcient materials forresisting and retaining food products either hot or cold, andparticularly those 5 products which are ,greasy or oily, is celluloseitself, which has lbeen treated until it is partly or whollygelatinized. This gelatinized or gel-like material will, when dryeffectively resist the at tack of the oils, greases and moisture of foodl0 products and what isA equallyimportant is that this material containsno contaminating matter which may affect the quality of any food productwith which it'comes in contact, as is the case with many of thechemicals and extraneous materials utilized as fillers, liners, or toprotect the surface of food containers.

While gelatinized cellulose is peculiarly adapted and extremely usefulin connection with containers for food products, its behavior duringmanufacture into, or as a part of a container, has

presented annoying manufacturing dimculties.

either to make the entire container or a substantial part of it. u

A method has been found, however, to obviate"l this particulardiillculty, which is the method of this invention. The article producedby] this' '35' method is simple and inexpensive to manufacture andfulfills the `requirements long y sought for butffI not previouslyobtained. y, ,f

Reference is made to the following gures illus-l trative of the articleand method of myV inven-' 40' tion.

Fig. 1 shows the portion of the article made from gelatinized cellulosematerials. v j Fig. 2 shows the body portion of the article which can bemade from any inexpensive fibrous` '45 or similar material. y Fig. 3 isan enlarged sectional view through] the material of Figs. 1 and 2 afterthey1 have ybeen' 1 j pressed together.

Fig. 4 illustrates a mechanism 'and methodby i which the materials ofFigs. l and `2 alrveunited,v bonded, dried and finished toformvthe`centaine or other article.

Fig. 5 is a cross-sectional view Ithroy h m nnishedarticle. v f. u

Fig. 6 is an enlarged cross-sectional viewthroughaportionofthefinishedarticle.

' Preferably I die-mould both the gelatinlsed material I, of Fig. i,andthe base-or body material2 onseparateforaminousdieshyanyconvenientmethod. When so formed I prepare the gelatinised material in such amanner that a certain portion ofthe fibre structure of the originalcellulose is retained while reducing to gel-like form a sumc'lentportion or part of the material` a filter-mat on which the finelydivided or gellike portion is retained and which otherwise would passthrough the foraminous die.

While this is my preferred method of producing the part of my articleindicated'at I, I do not, however, commit myself exclusively to thismethod. I may deposit this gelatinized materia directly upon thepreviously formed body portion 2, by utilizing this body portion 2, as afilter-mat, drawing thereon by suction or vacuum applied to one surfaceof body portion afilm or layer of the gelatinized material on the otheror exposed surface. Or, I may deposit on this body portion or on aseparate form or die,'a layer of this material by means other thansuction formation, such as spraying or similar means.

Regardless of how I may form either of the layers I or 2, I subsequentlyjoin them together as indicated in Fig. 8. The body layer I adiaeentnature of an ironing preure which imparts to to the gelatinised materialI, is left rough and somewhat uneven as'indicated at 3. for purposeshereinafter explained.

Having placed the two layers I and 2 together I now compress theselayers in any suitable device. One such device is illustrated in Pig. 4.Inthis figurethe two layers I and 2 are shown compressed between dies 4and l.v Pressure may be applied by any vsuitable means such as togglelevers t, operating between the die 4 and a xed abutment 1. This. or anyother suitable means maybe utilized to place pressureon the articleinterposed between the dies 4 and l.

To facilitate the evaporation and removal of moisture contained in theportions I and 2 I may apply heat in any suitable manner to the dieswhich compress the article.

means may be introduced through pipe l. 'Ihe die 4 consists of an innerwall I4, the exterior surface of which conforms tothe desired nnishedshape of the inside of the article. The chamber 8 is enclosed by anouter` wall I I so that pressure can -be established in thechamber 2should this be desirable. l

In order that the two portions from which this article is to be made,are firmly held under compression and against. the wall Il of die 4 Iprovide a second die-I having an interior wall I2,

outside of which lmay be covered with a perforated material I3 throughwhich the evaporated ,fmoisture escapes passing through holes i4 in ftheinner wall I2 of the die 5. A chamber I6 is provided this being closedbetween the inner wall I2 ,andthe outerwall Il. .'Ihe moisture ofevaporation escapes through holes I4 in the inner wall or be drawn oil.through the pipe I8.

.-.If desired, I mayapply heat to the die I to assist in evaporation bythe addition of a heating As shown. die 4 is y .provided with a chamberl, in whichv heating chamber I0. enclosed between the walls I5 and a newouter wall 2l. This chamber may .be heated by Vapor introduced throughpipe 2I or any other convenient means.

It has already been mentioned that the material utilised fo'r part I Yofthe article shrinks greatly when ,the water contained in this materialis removed by drying. The body or base material 2 has negligibleshrinkage on-\drying and there is indicated somewhat diagrammatically bythe dotted line I-A in Fig. l the relative size of portion I were itallowed or permitted to dry naturally.

It has also been pointed out that the exterior surface 2 of part 2 ofthe article is intentionally left somewhat rough and uneven and againstand on this rough surface under considerale pressure the portionl isheld as has already been described and illustrated in'Fig. 4.

Now as already stated. .the characteristics of the material which I usefor Fig. l are such that this material will shrink and must be allowedto do so but of course, if allowed to shrinkfnormally as illustrated atI--A of Fig. l it would have no utili'ty or value for the article ofwhich it forms a part.

Consequently instead of allowing or permitting this gelatiitiilledmaterial I to shrink normally,-it is held under pressure and heatagainst a relatively rough and uneven pulp surface, so that thenecessary shrinkage which this material must have will be only in thedirection of the thickness of the article as indicated by the arrow 22in Fig. 3. 'I'he pressure on this portion of the articleduring dryingimparted by the die 4 is in the the layer I a substantially smoothironed surface. "I'he heat and pressure is sumcient to bond the layers Iand 2 and dry the article without appreciable distortion ory appreciableshrinkage thereof in a direction coextensive with the surface of thearticle. In this bonding and drying action the roughness of the surface3 with which this layer I is in contact, prevents it from shrinking inwhole or in any part thereof, parallel to its surface but shrinkage isonly permitted in the direction of thickness or in the direction of thearrow 22. As the moisture leaves part I this layer grows thinner and thedies 4 and i comecloser together following up the shrinkage of layer Iinsuring that it not 'only remains in intimate contact with layer 2 butthat no part of it be allowed to move or change its position which wouldresult in a rupture or crack in its surface destroying its utility forthe purpose intended.

. In Fig. 6 there is illustrated an enlarged cross section through thefinished article, after the layer I by compression and heat, has beenreduced in thickness to make` up for its natural shrinkage remainingfirmly in contact with the base sheet 2 throughout the surface and areaof the finished article. It is important that the lpart I be held firmlywith the roughened part 2 until all or practically all of the moisturelhas been evaporated, otherwise part I may become loosened from part. 2even though only.a small fraction of moisture remains therein.

I am aware that various suggestions have been made as to the use ofgelatinized cellulose materials as a surface coating for flat sheets ofpaper or thin board. 'Ihese suggestions and disclosures failed utterlyto indicate or even to suggest any method by which two materials ofwidely varying shrinkage characteristics can be firmly afllxed to eachother in a simple manner. It is equally obvlous that even if flat sheetsof paper or board employing material of this invention were avail- Iablethat this board could not be formed satisfactorily into a dish orcontainer without destroying its utility and rupturing one or more ofthe layers of which the board might be made up. Hence, the varioussuggestions previously mentioned for applying adhesive to previously cutsheets and of forming these sheets up into the container.

The simplicity of the materials selected t0- gether with the developmentof a method of successfully utilizing the value of these materials hasresulted in the production of a new product of great commercial valueand utility.

Having thus described my invention, what I desire to claim is- 1. Themethod of manufacturing a multi-layer molded pulp contoured article as aplate, dish, cup or other shaped article, which comprises forming fromfibrous pulp a plurality of wet article layers correspondingsubstantially in size and shape to the size and shape of the ultimatearticle, one of said layers being composed in part at least ofcellulosic brous material of gel-like characteristic which layer whendried effectively resists penetration of moisture grease and oiltherethrough, uniting said layers in superimposed order as a compositearticle, and confining the composite article between a pair of diessubstantlally corresponding in size and shape to the formed articlelayers while simultaneously applying sufficient heat and pressure oversubstantially the entire surface of the article to bond the layers anddry the article without appreciable distortion or appreciable shrinkagethereof in a direction coextensive with the surface of the article.

2. `The method of claim 1, the article layers being independently formedon independent contoured foraminous forming dies.

3. The method of claim 1, the article layers being successively formedon a single contoured foraminous forming die.

4. The method of claim 1, and the step of exhausting from one of saiddies the water or water vapors given oii' by the drying article duringtheI drying period.

5. A`n individual multi-layer molded pulp article of dished shape,consisting of a plurality of superimposed pre-shaped ilbrous layers, oneof s aid layers being composed of gel-like brous material which in driedstate forms a hard, tough but flexible layer effectively resistingpenetration of moisture, grease and oil, said last named layer beingpartly forced into the surface of the other layerv and exhibiting asubstantially smooth ironed surface.

